Adjustable centrifugal switch assembly



Jan. 15, 1957 w, s, JR 2,777,912

ADJUSTABLE CENTRIFUGAL SWITCH ASSEMBLY Filed May 21, 1954 INVENTOR.WllZLCLlTl A.Hau1es,lr.

WMVM ATTORNEY;

.inited States Patent @fifice 2,777,912 Patented Jan. 15, 1957ADJUSTABLE CENTPJFUGAL SWITCH ASSEMBLY William A. Haines, Jr., Troy,Ohio, assignor to O. Smith Corporation, Milwaukee, Wis., a corporationof New York Application May 21, 1954, Serial No. 431,529

7 Claims. (Cl. 20080) This invention relates to a centrifugally actuatedswitch and particularly to a switch which is adjustably mounted inrelation to a centrifugal actuator.

In the mounting of a centrifugal switch in relation to its actuator,various factors such as contact clearance and pressure and switchclearance are critical.

In accordance with the present invention a switch is constructed in aself-contained manner to automatically set the required clearances andpressure. Further, the switch is provided with a pivotal attachmentwhich permits easy initial setting and positive clamping so that theoriginal setting cannot be disturbed.

More particularly, the switch is a self-contained unit having thenecessary contact clearance and pressure. The switch is adjustablyattached to the actuator, such that when the actuator, in anon-responsive position, engages the switch in a closed position, theassembly is correctly adjusted.

Therefore, one object of the invention is to provide an adjustablecentrifugal switch assembly with an improved attachment construction.

The drawing furnished herewith illustrates the best mode presentlycontemplated for carrying out the invention.

In the drawing:

Figure 1 is a view partly in section of the switch and actuator in anon-responsive position;

Figure 2 is an elevational view of the actuator, viewed from the rightin Figure 1;

Fig. 3 is an elevational view of the switch, viewed from the left inFigure 1;

Fig. 4 is a reduced elevational view of the switch, with the coverremoved, as viewed from the right in Figure 1; and

Fig. 5 is a similar view of the switch cover, viewed from the left inFigure 1.

Referring particularly to Figure l, a centrifugal actuator 1 is securedto the end of a rotatable shaft 2 which is journaled in a bearing 3. Aswitch 4 is secured to a stationary bearing support 5 of bearing 3 andin spaced relation to the actuator 1.

The actuator 1 is of a conventional variety having a pivotal weightedswitch actuating member or operator 6 disposed transversely of the shaft2 and responsive to a predetermined speed of rotation of the shaft 2 toactuate the switch 4. The operator 6 is provided with a pair oftransversely extending ears 7 trunnioned in the upper portion of theside arms 8 of a support bracket 9. The side arms 8 are in spacedparallel relation with the operator 6 disposed therebetween. To bias theoperator 6 to a non-responsive position, a pair of longitudinal springs10, one secured to each exterior side of arms 8, are provided with hookson both ends thereof with the hooks of each spring engaging respectivelya lug 11 on the op erator and a lug 12 on the side arms 8. The springsbias the weighted end of the operator 6 downwardly into engagement witha web portion 13 of the bracket 9 extending above the shaft 2. In thisposition the lower end of the operator 6 is biased upwardly andoutwardly, holding the contacts 14 of switch 4 in a closed position.

Each arm 8 has a vertical extension 15 disposed in the path of theoperator 6 and limiting the pivotal movement of the operator. Themovement or" the operator 6 is therefore between the top of the webportion 13 and the extensions 15 which movement is sufficient tocompletely disengage the switch 4, as subsequently described.

The actuator 1 is secured to the end of the shaft as by a bolt 16passing through an opening in the web 13 of bracket 9 and threaded intothe center of the shaft 2.

Referring now to switch 4 the contacts 14 of the switch are totallyenclosed by a generally rectangular housing consisting of an inner wall17 and an outer wall or cover 18 constructed of a suitable electricallyinsulating material.

The inner wall 17 is provided with sides 19 which extend to the outerwall or cover 18 and define a switch chamber. The walls 17 and 18 areprovided with matching flanges 20 through which rivets 21 extend andhermetically join the walls.

A metal strip spring 22 is disposed within the housing and is secured atone end to the interior surface of the wall 18 as by rivets 23 andcarries at its other free end a floating contact 24 of contacts 14. AnL-shaped connector 25 is secured to the exterior surface of wall 18 bythe lower rivets 23 to provide for the connection of contact 24 in anelectrical circuit, not shown. The spring 22 is secured to an enlargedlower portion 26 of the outer wall 18 to permit floating movement of thecontact 24.

The spring 22 is prestressed such that the contact 24 is biased towardthe wall 17. The free end of spring 22 is provided with transverselyextending cars 27 which engage small protrusions 28 extending from thesides 19 of wall 17 to limit the movement of the spring 22. Theprestressing of the spring 22 provides the desired contact pressure forcontacts 14, when in a closed position, with optimum contact clearancewhen in an open position.

A metal strip spring 29, similar to the spring 22, is secured at itslower end to the interior surface of wall 17 as by rivets 30 and carriesat its free end the movable contact 31 of contacts 14 in alignment withcontact 24. The spring 29 is prestressed, similar to spring 22, to biasthe upper end of the spring 29 against the inner wall 17 i with thecontact 31 disengaged from contact 24 a predetermined distance toprovide the desired contact clearance therebetween in open condition.

The outermost portion of the free end of spring 29 has a generallyU-shaped portion 32 with the shaft of the switch operating button 33passing therethrough and with the tips of the U-shaped portion crimpe-dtoward the inner wall 17 as at 34. A generally L-shaped connector 35 issecured to the exterior surface of wall 17 by the lower rivet 30 toprovide for the connection of contact 31 in an electrical circuit, notshown.

The button 33 has an enlarged portion 36 journalled in an opening in atubular extension 37 of the inner wall 17. The opening through which theenlarged portion 36 of button 33 passes is hermetically sealed by arubber boot 38 which is generally tire-shaped with the ends fittingtightly in a ring groove in the exterior end of the button 33 and a ringgroove in the tubular housing extension 37. The boot 38 in addition tohermetically sealing the opening prevents the button 33 from turning inthe extension 37 and therefore reduces wear on the button.

A flange 39 at the innermost end of button portion 36 provides a stop tolimit the outward travel of the button spring 29 to move the contact 31.The U-shaped portion 32 of the spring 29 provides a balanced pressure attwo diametrically opposite points of the button 33 and prevents thetendency of the button to bind in the guide opening as it is moved. Whenthe button 33 moves inwardly, the flange 39 engages the spring 29 at 34and moves the contact '31 toward contact 24.

The inner end of the shaft of button 33 is slidably mounted in acylindrical recess 40 in the outer wall 18 and the inward travel of thebutton 33 is limited by the engagement of the button and the bottom ofrecess 40.

The button 33 is constructed in cooperation with the prestressed springs22 and 2-9 such that the desired contact pressure is obtained when thebutton 33 moves to its innermost position and such that thedesiredcontact clearance is obtained when the button 33 moves to itsoutermost position. Further, the distance the button 33 travels betweenits outer and innermost positions is less than the travel of theoperator 6 and therefore the button 33 and operator 6 are disengaged inthe responsive position, as previously noted The switch 4 is secured tothe support with the button 33 disposed in thepath of the operator 6 andwith the button in its innermost Position when. the .operator 6 is in anon-responsive position, as shown inl-" igure 1.

The switch 4 is attached in place by a channel-shaped bracket 41 whichis bolted to the stationary support 5 as at 42. The sides 43 of thebracket extend upwardly to support the switch 4 with the button 33in thepath of operator 6. The switch ,4 ,is secured to the bracket 41 by anupper bolt 44 and a lower b lt 45 each of which passes through alignedopenings in the bracket sides and a transverse opening ,in the innerwall 17 of he switch, the inner wall 17 being suitably thickenedtransversely to provide the Ieqniredbolt openings.

The upper opening in the wall of the switch isfenlarged toform anelongated slot 46 allowing limited pivotal movement about thelower bolt45. i

In assembly, the actuator 1 is first secured, to shaft 2. The switch 4is pivotally secured to thebracket 41 and pivoted against the switchoperator 6 until the button 3,3 lightly engages the bottomvofthe recess4.0. While the button 33 is held against the bottom of recess 40, bolts44 and 45 are tightened to hold the switch in place. Thereafter theresilience in the complete system disengages the button 33 from thebottom ..of the recess ,40Qso that no force over and above that exertedby springsIZZ and 29 is applied through button 33 to the operator .6.This disengagement is in the order of a few thousandths of an inch whichis indicated in an exaggerated manner in Figure 1 as at 47 and is'suflicient to prevent undue pressure on operator 6 which might force itto operate at an unintended lower speed. The actuator 1 and switch 4 arethen in the position illnstratedi-n Figure 1. The position of theactuator 1 and switch 4 in aresponsive position is shown in Figure lbythedashed-lineposition of the operator 6 and button '33.

Theoperation of the actuator and switch is .as follows:

,At a predetermined speed of rotation wat the shaft 2, the centrifugalforce acting on the operator 6 overcomes the force of the longitudinalsprings with a resultant pivoting of the operator 6. The operator 6disengages the button 33 and the contacts 14 are instantly opened as aresult of the prestressing of s prings 22 and '29 toward the wall 17. Vi

As previously noted, the switch 4 is constructed such that the limitedmovement of the button 33 provides thedesired contact clearance andcontact pressure for the contacts 14 when the button is in its outermostand innermost positions, respectively. The mounting method describedprovides an ,accurate and simple .rnanner of switehlooation forareguired contactseparation whenthe switch-is open and contact pressurewhen the switch is closed.

Various embodiments of the invention may be employed within the scope ofthe following claims.

I claim:

1. The combination of a switch member and centrifugal actuator with saidactuator being mounted on a rotatable shaft and having a switchactuating member responsive to a predetermined speed of rotation of theshaft, said switch member comprising a housing, a pair of resilientswitch contacts secured within said housing, switch means extendingbetween one of said contacts and the switch actuating member and adaptedto engage and disengage the contacts upon actuation by the switchactuating member, stop means in the housing in the path of the switchmeans to limit the movement of the switch means by the switch actuatingmember when the switch means is initially assembled with said switchactuating member, a frame disposed adjacent the rotatable shaft,adjustable securement means securing the switch housing to said frame sothat when the switch member is initially assembled with the centrifugalactuator prior to a clamp ing of the securement means and the shaft isin nonro'tating position the switch actuating member is disposed inengagement with the switch and the switch means is manually held inengagement with the stop and the contacts are in engagement with eachother whereby the switch member is accurately located re1ative to thecentrifugal actuator, and a relief space being formed between saidswitch means and the stop means upon release of the switch means after aclamping of the securement means to thereby eliminate undue pressure on'the actuator that might result in its operation atan unintended lowerspeed.

i 2. The combination of a switch and centrifugal actuator, said actuatorbeing mounted on a rotatable shaft extending from a motor with which thecombination is employed and having a switch actuating member responsiveto'a predeterminedspeed of rotation of the shaft, said switch membercomprising a housing, a pair of resilient switch contacts secured withinsaid housing, switch means extending between one of said contacts andthe switch actuating member and adapted to engage and disengage thecontacts upon actuation by the switch actuating member, stop means inthe housing in the path of the switch means to' limit the movement ofthe switch means by the switch actuating member when the switch means isinitially assembled with said switch actuating member, a frame in which,the shaft is journaled and disposed adjacent the housing, a bolt meanssecuring the housing of the ,switch member to the frame adjacent the endof the housing removed from the switchmeans, a transverse slot in thehousing between the bolt means and the switchnneans, a second bolt meansextending through the slot with said slot permitting manual pivoting ofthe housing onthe first named bolt means upon initial assemblynof theswitch member and centrifugal actuator to at that time dispose theswitch actuating member in engage ment with the switch and to hold theswitch means in engagement with the stop and the contacts in engagementwith each other whereby the switch member is accurately located relativeto the centrifugal actuator, and a relief space being formed betweensaid switch means and the stop upon the manual release of the switchmeans as a result of the resilience of the switch mounting to therebyeliminate undue pressure on the actuator that might result' in itsoperation at an unintended lower speed.

3. In combination, a centrifugal actuator mountedon a rotatable shaftand having switch actuating mechanism with an axial movement, a pair ofcontacts resiliently mounted on a support disposed adjacent said switchactuating mechanism with one of said contacts being adapted to bemovedby said mechanism and both of said contacts being biased oward said a mehan pm an .1. s i support limitingthe movement of the contacts towardsaid actuator and providing a predetermined contact clearance betweenthe contacts in open position, a second stop means on said supportlimiting the movement of the contact moved by the switch actuatingmechanism to provide a predetermined contact pressure between thecontacts in closed position, and adjustable means securing said supportfor the contacts in place relative to said actuator to provide for fullmovement of the contact actuated by the actuating mechanism between saidstop means and to effect a positioning of the support and actuatorwithout close tolerance demands on the securing means and with out trialand error tensioning of said resilient contacts.

4. In combination, a centrifugal actuator secured to a rotatable shaftand having a switch operator responsive to a predetermined speed ofrotation, and a switch unit comprising a housing pivotally mounted inspaced relation to said actuator, a pair of leaf springs disposed withinthe housing and secured at one end to said housing in spaced relation toeach other, a contact on the free end of each of said leaf springs ingeneral alignment with each other, said leaf springs being prestressedto effect a bias of the contacts in the same direction and one of saidleaf springs being moved in response to movement of said operator andthereby alternately opening and closing the contacts on said springs,stop means in the housing in the stressed-wise path of said leaf springsto provide a predetermined clearance between the contacts in an openposition, a second stop means in the housing to limit the movement ofsaid leaf springs in closing the contacts and thereby provide apredetermined contact pressure between said contacts in a closedposition, and means to secure said housing in a predetermined fixedrelation to said actuator with said contacts in closed position wherebythe mounting of the actuator and contacts is facilitated.

5. In combination, a centrifugal actuator mounted on a rotatable shaftand having a switch operator responsive to a predetermined speed ofrotation of said shaft, a switch contact housing pivotally mountedadjacent said operator on a frame supporting said shaft, a leaf springsecured at one end to said housing and having the other end disposed inthe path of said operator, said leaf spring being prestressed towardsaid operator, stop means extending from said housing into the path ofsaid leaf spring between the spring and the actuator, a contact securedto the free end of said leaf spring, a second leaf spring secured at oneend to said housing in spaced and aligned relation to said first leafspring, said second named leaf spring being prestressed toward saidfirst named leaf spring, a contact secured to the free end of saidsecond leaf spring and disposed in alignment with said first namedcontact, stop means located in said housing in the stressedwise path ofsaid second spring to provide a predetermined clearance between saidcontacts, stop means located in said housing and limiting the contactengaging movement of said first leaf spring to provide a predeterminedpressure between the contacts when said contacts are closed, and saidhousing being secured to the frame when said contacts are in closedposition and the first named leaf spring is engaged by said operator toassemble the actuator and switch contacts for accurate operation.

6. In combination, a centrifugal actuator support mounted on the end ofa rotatable shaft, a switch operator pivoted on said supporttransversely to the axis of the shaft to effect axial and shaft-wisemovement of a portion of the operator in response to a predeterminedspeed of rotation of the shaft, a spring biasing said operator to anon-responsive position, a switch contact housing disposed adjacent saidshaft on a frame supporting said shaft, a leaf spring secured at one endto said housing and having the other end unsecured, said leaf springbeing prestressed to bias its unsecured end toward said operator, aportion of the housing disposed to engage said leaf spring and limit theoperator-wise movement of the spring, a contact attached to theunsecured end of said leaf spring, a second leaf spring attached at oneend to said housing diametrically opposite and in alignment with saidfirst leaf spring, a contact attached to the unsecured end of saidsecond leaf spring and aligned with said first contact, said last namedleaf spring being stressed to bias said second contact toward said firstcontact, a portion of said housing disposed in the stress-wise path ofsaid second spring to effect a predetermined clearance between saidcontacts, a contact lever journaled in the walls of said housing andadapted to move said leaf spring to effect engagement between saidcontacts, a lever stop portion of said housing disposed in the contactengaging path of said lever to provide a predetermined contact pressure,and pivotally attaching means adapted to secure said housing to theframe when the contact lever is engaging said operator and said leverstop portion, said construction eliminating close tolerances inassembling the actuator support and the switch housing and eliminatingtrial and error stressing of said leaf springs to obtain thepredetermined contact clearance and pressure.

7. In combination, a frame, a channel-shaped support having a websecured to an end of a rotatable shaft supported by said frame with saidsupport having axially extending sides with aligned openings in theupper portion thereof, a switch operator having ears extending into saidopenings to support the operator for pivotal movement, spring meansbiasing said operator to a non-responsive position with a projection onsaid operator extending axially outwardly of the shaft, said operatorresponding to a predetermined speed of rotation of the shaft to movesaid projection of the operator generally axially toward said shaft, ahollow switch housing disposed adjacent said shaft and having verticallyspaced openings in one wall to receive attachment bolts for securing thehousing to said frame, one of said openings being in the form of atransverse slot to effect limited pivotal movement of the housing aboutthe other of said openings and the wall of the housing having saidopenings being disposed transversely to said shaft, a contact rodjournaled in one end of said housing and aligned with the projection ofsaid operator, a leaf spring attached at one end to the inside of saidhousing and having the other free end adapted to be engaged by saidcontact rod, a contact affixed to the free end of said leaf spring, saidleaf spring being prestressed a predetermined degree toward saidoperator to bias said rod toward the operator, a second leaf springattached at one end to the inside of said housing and spaced from andlongitudinally aligned with said first named leaf spring, a contactafiixed to the unsecured end of said second leaf spring in alignmentwith said first named contact, said second leaf spring being prestresseda predetermined degree toward said first leaf spring, protrusions on theinside of said housing engaging said second leaf spring and holding thesecond spring a predetermined distance from the first spring to providea predetermined contact clearance, said contact rod extending outwardlyof the housing and being engaged by said operator when the operator isin a non-responsive position and the opposite end of the contact rodbeing journaled in a recess in a wall of the housing with the base ofthe recess limiting the movement of said rod to effect the engagement ofsaid contacts with a predetermined contact pressure, and said switchhousing being secured to said frame when the contacts are in an engagedposition and the contact rod is engaged with the operator disposed in anon-responsive position, said construction facilitating the mounting ofthe combination on the shaft and bracket.

References Cited in the file of this patent UNITED STATES PATENTS

